The present invention relates to articles of footwear in general, especially to articles of outer footwear, and more particularly to improvements in the bases of such articles of footwear (hereinafter called shoes for short). Still more particularly, the invention relates to improvements in footwear bases which are made of elastically deformable and compressible material so that the bases can yield in response to the application of stresses and shocks by the feet of the wearers of the shoes.
German Offenlegungsschrift No. 1 485 580 discloses a shoe whose base has a recess below the heel of the foot. This is supposed to enhance the stability of the base on the floor or on the ground and to furnish a desirable damping action. The recess is surrounded by a rather wide ridge whose purpose is to protect the heel during jumping and the resulting pronounced impacts of the heel portion of the base against the ground or floor.
U.S. Pat. No. 4,259,792 discloses an article of outer footwear wherein the heel portion of the base is also formed with a recess to enhance the shock absorbing characteristics of the base.
German Offenlegungsschrift No. 27 52 300 discloses a shoe wherein the underside of the heel has an uneven and slanting rear portion in order to enhance the rolling action of the heel in response to initial contact with the floor or ground.
Attempts to enhance the comfort of the foot during jumping, walking, jogging or running include the provision of footwear bases with profiled upper surfaces. Such proposal is not entirely satisfactory because the configuration of the prefabricated upper surface of the base may or may not conform to the shape of the foot of the purchaser of the shoe. In fact, such bases are likely to cause pronounced discomfort to the wearer of the shoe and can lead to twisting of the ankle and/or other injuries. Furthermore, such bases are likely to inadequately support the foot so that the wearer is tired after a relatively short period of exercising or walking and the feet of the user are likely to be deformed as a result of the use of such shoes.